Modular cytosine base editing promotes epigenomic and genomic modifications.

Prokaryotic and eukaryotic adaptive immunity differ considerably. Yet, their fundamental mechanisms of gene editing via Cas9 and activation-induced deaminase (AID), respectively, can be conveniently complimentary. Cas9 is an RNA targeted dual nuclease expressed in several bacterial species. AID is a cytosine deaminase expressed in germinal centre B cells to mediate genomic antibody diversification. AID can also mediate epigenomic reprogramming via active DNA demethylation. It is known that sequence motifs, nucleic acid structures, and associated co-factors affect AID activity. But despite repeated attempts, deciphering AID's intrinsic catalytic activities and harnessing its targeted recruitment to DNA is still intractable. Even recent cytosine base editors are unable to fully recapitulate AID's genomic and epigenomic editing properties. Here, we describe the first instance of a modular AID-based editor that recapitulates the full spectrum of genomic and epigenomic editing activity. Our 'Swiss army knife' toolbox will help better understand AID biology per se as well as improve targeted genomic and epigenomic editing.

Nail it! vision-based drift correction for accurate mixed reality surgical guidance.

PURPOSE: Mixed reality-guided surgery through head-mounted displays (HMDs) is gaining interest among surgeons. However, precise tracking of HMDs relative to the surgical environment is crucial for successful outcomes. Without fiducial markers, spatial tracking of the HMD suffers from millimeter- to centimeter-scale drift, resulting in misaligned visualization of registered overlays. Methods and workflows capable of automatically correcting for drift after patient registration are essential to assuring accurate execution of surgical plans. METHODS: We present a mixed reality surgical navigation workflow that continuously corrects for drift after patient registration using only image-based methods. We demonstrate its feasibility and capabilities using the Microsoft HoloLens on glenoid pin placement in total shoulder arthroplasty. A phantom study was conducted involving five users with each user placing pins on six glenoids of different deformity, followed by a cadaver study by an attending surgeon. RESULTS: In both studies, all users were satisfied with the registration overlay before drilling the pin. Postoperative CT scans showed 1.5 mm error in entry point deviation and 2.4[Formula: see text] error in pin orientation on average in the phantom study and 2.5 mm and 1.5[Formula: see text] in the cadaver study. A trained user takes around 90 s to complete the workflow. Our method also outperformed HoloLens native tracking in drift correction. CONCLUSION: Our findings suggest that image-based drift correction can provide mixed reality environments precisely aligned with patient anatomy, enabling pin placement with consistently high accuracy. These techniques constitute a next step toward purely image-based mixed reality surgical guidance, without requiring patient markers or external tracking hardware.

Biomechanical Stability of Lateral Ulnar Collateral Ligament Reconstruction and Repair of the Elbow: The Role of Ligament Bracing on Gap Formation and Stabilization.

BACKGROUND: Augmented (internal braced) lateral ulnar collateral ligament (LUCL) repair has been biomechanically compared with reconstruction techniques in the elbow. However, LUCL repair alone has not yet been compared with augmented repair and reconstruction techniques. HYPOTHESIS: Internal bracing of LUCL repair would improve time-zero stabilization regarding gap formation, stiffness, and residual torque as compared with repair alone and reconstruction techniques to restore native elbow stability. STUDY DESIGN: Controlled laboratory study. METHODS: Overall, 24 cadaveric elbows were used for either internal braced LUCL repair (Repair-IB) or single- and double-strand ligament reconstruction with triceps (Recon-TR) and palmaris longus tendon graft (Recon-PL), respectively. Laxity testing in external rotation was consecutively performed at 90° of elbow flexion on the intact, dissected, and repaired conditions and with the previously assigned techniques. First, intact elbows were loaded to 7.0-N·m external torque to evaluate time-zero ligament rotations at 2.5, 4.0, 5.5, and 7.0 N·m. Rotation-controlled cycling was performed (total of 1000 cycles) for each surgical condition. Gapping, stiffness, and residual torque were analyzed. Finally, these and 8 additional intact elbows underwent torque-to-failure testing (30 deg/min). RESULTS: The dissected state showed the highest gap formation and lowest peak torques (P < .001). While gap formation of Repair-IB (P < .021) was significantly lower than that of repair without internal bracing at all rotation levels, gaps of Recon-PL were similar to and Recon-TR were significantly higher than those of Repair-IB except for the highest torsion level. Residual peak torques at specific rotation angles between native state and Recon-TR (α2.5), Recon-PL (α4.0), and Repair-IB (α5.5) were similar; all other comparisons were significantly different (P < .027). Torsional stiffness of Repair-IB was significantly higher at all rotation angles measured. Analysis of covariance showed significantly less gap formation over residual peak torques for Repair-IB (P < .001) as compared with all other groups. The native state failure load was significantly higher than Recon-PL and Recon-TR failure loads, with similar stiffness to all other groups. CONCLUSION: Repair-IB and Recon-PL of the LUCL showed increased rotational stiffness relative to the intact elbow for restoring posterolateral stability to the native state in a cadaveric model. Recon-TR demonstrated lower residual peak torques but provided near-native rotational stiffness. CLINICAL RELEVANCE: Internal bracing of LUCL repair may reduce suture-tearing effects through tissue and provide sufficient stabilization for healing throughout accelerated and reliable recovery without the need for a tendon graft.

Cumulative group metrics: a new and efficient method to measure the scientific impact of research groups.

Various metrics have emerged for assessing scientific impact, most of which are based on complex calculations and, in many cases, are not freely available. Moreover, most of these metrics are not intended for assessing the scientific impact of research groups. Cumulative group metrics are proposed as an efficient and cost-effective strategy for measuring group scientific impact. Materials and methods: The authors collected peer-reviewed output in 2020 from two academic orthopedic surgery departments [University of Michigan (UM) and Mayo Clinic Rochester (MC)] and one medical device research department [Arthrex Inc. (AI)]. The sites evaluated the Cumulative Group Number of Publications (CGNP), Cumulative Journal Impact Factor (CJIF), Cumulative CiteScore (CCS), Cumulative SCImago Journal Rank (CSJR), and Cumulative Source Normalized Impact per Paper (CSNIP) for the three institutions. Results: In 2020, UM published 159 peer-reviewed studies, MC published 347 peer-reviewed studies, and AI supported 141 publications. The UM publications achieved a CJIF of 513, a CCS of 891, a CSJR of 255, and a CSNIP of 247. The MC publications achieved a CJIF of 956, a CCS of 1568, a CSJR of 485, and a CSNIP of 508. AI-supported publications achieved a CJIF of 314, a CCS of 598, a CSJR of 189, and a CSNIP of 189. Conclusion: The presented cumulative group metrics are an effective tool to assess the scientific impact of a research group. The cumulative submetrics can further evaluate research groups compared with other departments due to field normalization. Department leadership and funding agencies can utilize these metrics to evaluate research output quantitatively and qualitatively.

Postoperative recovery comparisons of arthroscopic Bankart to open Latarjet for the treatment of anterior glenohumeral instability.

BACKGROUND: Recurrent anterior glenohumeral instability is a disabling pathology that can be successfully treated by arthroscopic Bankart repair or open Latarjet. However, there is a paucity of studies comparing the postoperative recovery. The purpose of this study is to evaluate the postoperative pain and functional recovery following arthroscopic Bankart versus open Latarjet. METHODS: This is a retrospective analysis of a multicenter prospective outcomes registry database. Postoperative recovery outcomes of either a primary or revision arthroscopic Bankart and open Latarjet procedures were compared. A minimum of 1-year follow-up was required. Outcomes measures included pain visual analog scale (VAS), American Shoulder and Elbow Surgeons (ASES) function score, ASES index score, and single assessment numeric evaluation (SANE) score. Overall, 787 patients underwent primary arthroscopic Bankart, 36 underwent revision arthroscopic Bankart and 75 underwent an open Latarjet procedure. RESULTS: When compared to primary arthroscopic Bankart, open Latarjet demonstrated significantly lower VAS scores at 6 weeks (p = 0.03), 3 months (p = 0.01), and 2 years (p < 0.05). Medium-term outcomes for ASES scores and SANE score, at 1 and 2 years showed no difference. Latarjet demonstrated significantly lower (p < 0.05) preoperative early postoperative VAS pain scores with no difference at 1 year or 2 years when compared to primary Bankart. There was no difference in ASES function or index between Bankart and Latarjet. Revision Bankart provided inferior outcomes for VAS, ASES function, and ASES index when compared to primary Bankart and Latarjet at 1 year and 2 years. CONCLUSIONS: Primary arthroscopic Bankart repair and open Latarjet provided nearly equivalent improvements in pain (VAS) and functional outcomes (ASES, SANE, VR-12) during the early recovery phase (2 years). This study supports the use of either procedure in the primary treatment of anterior glenohumeral instability. Revision arthroscopic Bankart repair demonstrated deteriorating outcomes at 1 and 2 years postoperatively.

Early postoperative recovery comparisons of superior capsule reconstruction to tendon transfers.

BACKGROUND: The management of massive posterosuperior rotator cuff tears is controversial, with no gold standard. Two recently developed techniques that have shown promising initial results include arthroscopic superior capsular reconstruction (SCR) and tendon transfers (latissimus or lower trapezius). However, there remains a scarcity of studies examining each procedure's early postoperative clinical outcomes individually or in comparison to each other. The purpose of this study is to compare the early postoperative recovery outcomes of tendon transfers (TTs) to SCR. METHODS: Using the surgical outcomes system global database (Arthrex Inc.), we assessed the postoperative recovery outcomes for all patients who had outcomes recorded at least 6 months after SCR or TT. The time points analyzed included preoperative and postoperative (2 weeks, 6 weeks, 3 months, 6 months, 1 year, 2 years). The outcomes analyzed included pain visual analog scale (VAS) score, American Shoulder and Elbow Surgeons Standardized Shoulder Assessment Form (ASES) score, VR-12 physical, and Single Assessment Numeric Evaluation (SANE). RESULTS: Overall, 163 patients underwent SCR and 24 arthroscopically assisted TT. The mean age for SCR and TT was 60 and 56 years, respectively. Postoperative recovery curves demonstrate that both procedures produced improved outcomes at each postoperative time point compared to preoperative. The pain and functional outcomes measures, including VAS, ASES, SANE, and VR-12 physical, were comparable for TT and SCRs, with similar recovery curves between the 2 techniques. Ultimately at 2 years postoperatively, there were no significant differences between the 2 techniques. CONCLUSIONS: Analysis of the early outcomes associated with arthroscopic treatment of massive posterosuperior rotator cuff tears demonstrated that the arthroscopically assisted tendon transfers and arthroscopic superior capsular reconstruction had similar pain and functional outcomes throughout the 2-year postoperative recovery period. Overall, the process of recovery appears equivalent between the 2 techniques. Future studies are needed to assess the outcomes of each technique and specific indications in an attempt to delineate an algorithm for the treatment of irreparable rotator cuff tears.

Partial Rotator Cuff Repair Provides Improved Patient-Reported Outcome Measures Following Superior Capsule Reconstruction (SCR).

Purpose: To evaluate the role of concomitant partial rotator cuff repair (RCR) (i.e., infraspinatus) on patient-reported clinical outcomes following superior capsule reconstruction (SCR). Methods: Postoperative recovery outcomes of SCR alone were compared with SCR with concomitant infraspinatus rotator cuff repair (SCR+RCR) at 3, 6, 12, and 24 months. Patients were included if they had an SCR surgery with or without a concomitant infraspinatus repair. Patients were excluded if they did not have a minimum of 6 months' follow-up or if a preoperative baseline questionnaire was not performed. Outcome measures included pain visual analog scale, American Shoulder and Elbow Surgeons (ASES) Shoulder Function, ASES Shoulder Index, and Single Assessment Numeric Evaluation (SANE) score. Results: Overall, 180 patients were evaluated, including 163 patients who underwent SCR alone and 17 patients who underwent concomitant infraspinatus repair (SCR+RCR). There was no difference in demographic data including age, sex, and body mass index. The postoperative recovery curves demonstrated SCR alone and SCR+RCR both provide significantly improved pain and functional scores at 2 years postoperatively (P < .001). When we compared the 2 groups, SCR+RCR provided significantly improved ASES Index (87.6 vs 78.2, P = .048) and ASES Function (25.5 vs 21.7, P = .02). There was no statistically significant difference in SANE scores (75.5 vs 64.2, P = .07) at 24 months' follow-up. Conclusions: SCR provides modest improvements in pain and function at 2 years postoperatively in patients with irreparable rotator cuff tears. Patients who underwent SCR and concomitant infraspinatus repair demonstrated significantly improved ASES Index and ASES Function scores and statistically nonsignificant improvement in SANE scores at 24 months postoperatively when compared with SCR alone. Level of Evidence: III, retrospective cohort study.

Obesity and sex influence fatty infiltration of the rotator cuff: the Rotator Cuff Outcomes Workgroup (ROW) and Multicenter Orthopaedic Outcomes Network (MOON) cohorts.

BACKGROUND: Fatty infiltration (FI) is one of the most important prognostic factors for outcomes after rotator cuff surgery. Established risk factors include advancing age, larger tear size, and increased tear chronicity. A growing body of evidence suggests that sex and obesity are associated with FI; however, data are limited. METHODS: We recruited 2 well-characterized multicenter cohorts of patients with rotator cuff tears (Multicenter Orthopaedic Outcomes Network [MOON] cohort [n = 80] and Rotator Cuff Outcomes Workgroup [ROW] cohort [n = 158]). We used multivariable logistic regression to evaluate the relationship between body mass index (BMI) and the presence of FI while adjusting for the participant's age at magnetic resonance imaging, sex, and duration of shoulder symptoms, as well as the cross-sectional area of the tear. We analyzed the 2 cohorts separately and performed a meta-analysis to combine estimates. RESULTS: A total of 27 patients (33.8%) in the Multicenter Orthopaedic Outcomes Network (MOON) cohort and 57 patients (36.1%) in the Rotator Cuff Outcomes Workgroup (ROW) cohort had FI. When BMI < 25 kg/m2 was used as the reference category, being overweight was associated with a 2.37-fold (95% confidence interval [CI], 0.77-7.29) increased odds of FI and being obese was associated with a 3.28-fold (95% CI, 1.16-9.25) increased odds of FI. Women were 4.9 times (95% CI, 2.06-11.69) as likely to have FI as men. CONCLUSIONS: Among patients with rotator cuff tears, obese patients had a substantially higher likelihood of FI. Further research is needed to assess whether modifying BMI can alter FI in patients with rotator cuff tears. This may have significant clinical implications for presurgical surgical management of rotator cuff tears. Sex was also significantly associated with FI, with women having higher odds of FI than men. Higher odds of FI in female patients may also explain previously reported early suboptimal outcomes of rotator cuff surgery and higher pain levels in female patients as compared with male patients.

A biomechanical comparison of subscapularis tenotomy repair techniques for stemless shoulder arthroplasty.

BACKGROUND: One of the leading challenges for surgeons shifting to stemless anatomic total shoulder arthroplasty (TSA) is subscapularis repair. In the available literature reporting outcomes after stemless TSA, subscapularis tenotomy with side-to-side repair is the most common technique despite some concerns regarding this technique in the biomechanical and clinical literature. Accordingly, this study investigated subscapularis tenotomy repair with stemless TSA with 2 primary objectives: (1) to evaluate the subscapularis tendon dimensions with reference to subscapularis tenotomy to determine the amount of tendon remaining for side-to-side repair after shoulder arthroplasty and (2) to biomechanically compare 2 methods of subscapularis tenotomy repair after stemless TSA-side-to-side repair and anchor-based repair. METHODS: We used 12 male shoulder specimens for this study. To address our first objective, measurements were made to calculate the dimensions of the subscapularis tendon at the superior, middle, and inferior levels to determine the amount of tendon remaining after tenotomy. These specimens were then divided into 2 groups (n = 6 in each group) to biomechanically compare subscapularis tenotomy repair with (1) traditional side-to-side repair and (2) anchor-based repair. The shoulders then underwent biomechanical testing with primary outcomes including load to failure and cyclic displacement. RESULTS: The mean subscapularis tendon width measured from the medial insertion at the lesser tuberosity to the muscle-tendon junction varied depending on the level: 19.5 mm superiorly (95% confidence interval [CI], 16.2-22.8 mm); 18.3 mm at the midportion (95% CI, 13.6-23.0 mm); and 13.1 mm inferiorly (95% CI, 9.1-17.1 mm). With a tenotomy made 1 cm medial to the lesser tuberosity insertion, a mean of 3.1 mm of tendon remained medially at the inferior subscapularis, with one-third of specimens having no tendon left medially at this level. On comparison of tenotomy repair techniques, the anchor-based technique had a 57% higher ultimate load to failure compared with the side-to-side repair (448 N vs. 249 N, P < .001). There were no significant differences in cyclic displacement (6.1 mm vs. 7.1 mm, P = .751) and construct stiffness (38.1 N/mm vs. 42.9 N/mm, P = .461) between techniques. CONCLUSIONS: With traditional techniques for subscapularis tenotomy for anatomic TSA, there is very little tendon remaining inferiorly for side-to-side repair. When subscapularis tenotomy is performed for stemless TSA, a double-row anchor-based repair has a better time-zero ultimate load to failure compared with side-to-side repair.

Independent Suture Augmentation With All-Inside Anterior Cruciate Ligament Reconstruction Reduces Peak Loads on Soft-Tissue Graft. A Biomechanical Full-Construct Study.

PURPOSE: To evaluate the effect of suture augmentation (SA) of 7-mm and 9-mm diameter graft on load sharing, elongation, stiffness, and load to failure for all-inside anterior cruciate ligament reconstruction (ACLR) in a biomechanical Study was funded by Arthrex ID: EMEA-16020. full-construct porcine model. METHODS: Bovine tendon grafts, 7-mm and 9-mm diameter, with and without SA were tested using suspensory fixation (n = 8). The independent SA was looped over a femoral button and knotted on a tibial button. Preconditioned constructs were incrementally increased loaded (100N/1,000 cycles) from 100N to 400N for 4,000 cycles (0.75 Hz) with final pull to failure (50 mm/min). Isolated mechanical and optical measurements during construct loading of the SA allowed to quantify the load and elongation range during load sharing. Construct elongation, stiffness and ultimate strength were further assessed. RESULTS: Load sharing in 7-mm grafts started earlier (200N) with a significant greater content than 9-mm grafts (300N) to transfer 31% (125N) and 20% (80N) of the final load (400N) over the SA. Peak load sharing with SA reduced total elongation for 7-mm (1.90 ± 0.27 mm vs 4.77 ± 1.08 mm, P < .001) and 9-mm grafts (1.50 ± 0.33 mm vs 3.57 ± 0.54 mm, P < .001) and adequately increased stiffness of 7-mm (113.4 ± 9.3 N/mm vs 195.9 ± 9.8 N/mm, P < .001) to the level of augmented 9-mm grafts (208.9 ± 13.7N/mm). Augmentation of 7-mm (835 ± 92N vs 1,435 ± 228N, P < .001) and 9-mm grafts (1,044 ± 49N vs 1,806 ± 157N, P < .001) significantly increased failure loads. CONCLUSIONS: Load sharing with SA occurred earlier (200N vs 300N) in lower stiffness 7-mm grafts to carry 31% (7-mm) and 20% (9-mm) of the final load (400N). Loads until peak load sharing were transferred over the graft. Augmented constructs showed significantly lower construct elongation and increased stiffness without significance between variable grafts. Failure load of augmented grafts were significantly increased. CLINICAL RELEVANCE: Suture tape ligament augmentation may potentially protect biological grafts from excessive peak loading and elongation, thus reducing the risk of graft tears.

Ibuprofen Use Did Not Affect Outcome Metrics After Arthroscopic Rotator Cuff Repair.

PURPOSE: To determine whether patients who are prescribed ibuprofen after arthroscopic rotator cuff repair have significantly different patient-reported outcomes for pain, function, and overall health at baseline and 1 and 2 years after operation relative to patients only prescribed opioids. METHODS: Patients who underwent a rotator cuff repair by a total of 3 surgeons and participated in the outcomes registry from 2012 to 2016 were screened for inclusion in this study. Inclusion criteria were primary arthroscopic rotator cuff repair, at least 2 years from the date of surgery and over the age of 18. Exclusion criteria were revision and open rotator cuff repair. All patients followed the standard postoperative rehabilitation protocol for rotator cuff repair. Patients were divided into 2 cohorts. Group I included patients who received ibuprofen/nonsteroidal anti-inflammatory agents (NSAID) after surgery (n = 281), and Group II consisted of patients who did not receive ibuprofen/NSAID after surgery (n = 182). Patient-reported outcome measures for Visual Analogue Scale, American Shoulder Elbow Surgeons score, Single Assessment Numeric Evaluation score, Simple Shoulder Test and The Veterans Rand 12-Item Health Survey were collected preoperatively and at 3 and 6 months, 1 year, and 2 years after surgery. Statistical analysis was performed to compare patient-reported outcome measures between Group I and II. RESULTS: This study consisted of 463 patients who underwent arthroscopic rotator cuff repair, and patients were divided into 2 cohorts. There were 281 patients who did not receive ibuprofen/NSAID after operation in Group I and 182 patients who did receive ibuprofen in Group II. There were no statistically significant differences between the 2 groups in age at treatment, mean body mass index, gender, ethnicity, diabetes, and number of rotator cuff tendons involved; however, there was a statistically significant difference in receiving worker's compensation (P = .005), and this was subsequently adjusted for in our analysis. There were no significant differences in patient-reported outcomes for all metrics between the group prescribed ibuprofen and the group that was not prescribed ibuprofen at 1 and 2 years after surgery or in change from baseline. CONCLUSION: Patients receiving ibuprofen did as well as patients who did not receive ibuprofen after arthroscopic rotator cuff repair on patient-reported outcome measures assessing shoulder pain, function, and overall health. LEVEL OF EVIDENCE: Level III, retrospective comparative study.

Biomechanical evaluation of 2 techniques of repair after subscapularis peel for stemless shoulder arthroplasty.

BACKGROUND: Stemless anatomic total shoulder arthroplasty (TSA) has been gaining significant popularity but poses unique challenges for subscapularis repair. Tenotomy with side-to-side repair has been the most frequently reported technique for subscapularis repair with stemless TSA but has the poorest biomechanical properties, and clinical failures have been reported. There is limited biomechanical evidence evaluating other subscapularis repair techniques for stemless TSA. Therefore, the goal of this study was to investigate 2 additional techniques using a subscapularis peel for subscapularis repair with a stemless TSA. METHODS: We used 18 male cadaveric specimens to investigate the native subscapularis (n = 6) and 2 subscapularis repair techniques (n = 12) after stemless anatomic TSA (Eclipse). A subscapularis peel with double-row, knotless anchor-based repair (n = 6) was compared with a subscapularis peel with a "backpack" repair (n = 6). The specimens then underwent biomechanical testing, including cyclic displacement and load-to-failure testing. The mode of failure was also recorded. RESULTS: The native tendon had the highest ultimate load to failure (mean, 1017.1 N). Load to failure was similar between the 2 study groups: 397.9 N for the peel and backpack repair and 593.7 N for the knotless anchor-based repair (P > .05 for all comparisons). Moreover, no significant differences in cyclic displacement or construct stiffness were found between the groups (P > .05 for all comparisons). CONCLUSIONS: A double-row, knotless anchor-based repair of a subscapularis peel for stemless anatomic shoulder arthroplasty has similar biomechanical properties to a backpack repair technique; however, both techniques fail to reproduce the native biomechanical properties at time zero.

Factors Associated With Symptomatic Rotator Cuff Tears: The Rotator Cuff Outcomes Workgroup Cohort Study.

OBJECTIVE: Although rotator cuff tear is one of the most common musculoskeletal disorders, its etiology is poorly understood. We assessed factors associated with the presence of rotator cuff tears in a cohort of patients with shoulder pain. DESIGN: From February 2011 to July 2016, a longitudinal cohort of patients with shoulder pain was recruited. Patients completed a detailed questionnaire in addition to a magnetic resonance imaging scan and a clinical shoulder evaluation. The association of multiple factors associated with rotator cuff tears was assessed using multivariate logistic regression. RESULTS: In our cohort of 266 patients, 61.3% of patients had a rotator cuff tear. Older age (per 1 yr: odds ratio = 1.03, 95% confidence interval = 1.02-1.07), involvement of the dominant shoulder (odds ratio = 2.02, 95% confidence interval = 1.16-3.52), and a higher body mass index (per 1 kg/m2: odds ratio = 1.06, 95% confidence interval = 1.03-1.12) were independently associated with rotator cuff tears. Sex, depression, smoking status, shoulder use at work, hypertension, and diabetes were not significantly associated with rotator cuff tear. CONCLUSIONS: In a cohort of patients with shoulder pain, we identified older age, involvement of the dominant shoulder, and a higher body mass index to be independently associated with rotator cuff tear. The mechanism of how these factors possibly lead to rotator cuff tears needs further research. TO CLAIM CME CREDITS: Complete the self-assessment activity and evaluation online at http://www.physiatry.org/JournalCME. CME OBJECTIVES: Upon completion of this article, the reader should be able to: (1) Identify factors associated with an increased risk of developing rotator cuff tears in adults; (2) Describe the current epidemiological trends of rotator cuff tears in the United States; and (3) Discuss the pathophysiological role of aging in the development of nontraumatic rotator cuff tears. LEVEL: Advanced. ACCREDITATION: The Association of Academic Physiatrists is accredited by the Accreditation Council for Continuing Medical Education to provide continuing medical education for physicians.The Association of Academic Physiatrists designates this Journal-based CME activity for a maximum of 1.0 AMA PRA Category 1 Credit(s)™. Physicians should only claim credit commensurate with the extent of their participation in the activity.

A Tensionable Suture-based Cerclage Is an Alternative to Stainless Steel Cerclage Fixation for Stabilization of a Humeral Osteotomy During Shoulder Arthroplasty.

INTRODUCTION: Fixation of periprosthetic humeral fractures is most commonly obtained with steel-based wires or cables; however, disadvantages with these constructs are numerous. Suture-based cerclages offer the advantage of easy handling, less radiographic interference, and risk of metallosis, as well as decreased risk of cutting into the soft humeral bone. Therefore, the purpose of this study was to compare a suture-based cerclage to a stainless steel wire cerclage (SSWC) for stabilization of the humerus during shoulder arthroplasty. METHODS: In part I of the study, SSWC fixation was compared with single-looped tape cerclage and a double-looped tape cerclage (DLTC) fixation. In part II, a subsidence test was performed on 12 cadaveric humeri. After an osteotomy, the humeri were secured with either a SSWC or DLTC. Subsequently, a metal wedge was introduced into the humerus to simulate the stem of a shoulder arthroplasty. RESULTS: In part I, load to 2-mm displacement was significantly higher for the DLTC construct compared with the SSWC construct (2,401 ± 483 N versus 750 ± 33 N; P < 0.0001). Load to failure was 935 ± 143 N with the SSWC, 1,737 ± 113 N with the single-looped tape cerclage, and 4,360 ± 463 N with the DLTC constructs, and all differences were statistically significant (P < 0.05). In part II, load at 20-mm subsidence was higher for the DLTC (320 ± 274 N) compared with the SSWC (247 ± 137 N), but no significant difference was observed (P > 0.05). However, gap displacement at 20 mm subsidence was significantly lower with the DLTC construct (0.33 ± 0.31 mm versus 0.77 ± 0.23 mm; P = 0.009). Load to failure was higher with the DLTC construct compared with the SSWC construct (4,447 ± 2,325 N versus 1,880 ± 1,089 N; P = 0.032), but the final gap displacement did not differ significantly (DLTC 5.23 ± 6.63 mm versus SSWC 6.03 ± 8.82 mm; P > 0.05). DISCUSSION: A DLTC has higher load to failure and trends toward lower gap displacement compared with a SSWC. The DLTC construct may therefore be a viable alternative for fixation of periprosthetic fractures or osteotomies of the humeral shaft during shoulder arthroplasty.

Neuroapraxia and early complications after reverse shoulder arthroplasty with glenoid bone grafting.

BACKGROUND: Bone grafting during primary reverse shoulder arthroplasty (RSA) is a technique used to restore poor glenoid bone, increase lateralization, and restore abnormal inclination or version. The purpose of this article is to analyze early outcomes of bone grafting during RSA, assessing the influence of technical and patient considerations. METHODS: In a 4.5-year time period, 137 RSAs with glenoid bone grafting were performed with a minimum 3 months' follow-up. The mean follow-up was 17 months (range, 3-38). The mean age was 71 years (range, 45-89), and body mass index was 28 (range, 19-44). The source of the autografts were humeral head (n = 113) and iliac crest autograft (ICBG; n = 24). The humeral components included 84 onlay and 53 inlay designs. RESULTS: Overall, there were 16 complications (12%), of which 6 were major (5%) (3 graft nonunions and 3 infections) and 10 minor (8%) (1 carpal tunnel syndrome and 9 transient axillary neuropraxias). Of the 9 axillary neuropraxias, 8 resolved by the most recent follow-up, whereas 1 patient was lost to follow-up. There were 4 reoperations (3%): 2 for glenoid baseplate loosening, 1 for severe notching associated with severe glenoid bone loss, and 1 for deep periprosthetic infection. One additional patient had a baseplate failure and is undergoing further treatment. There was no difference in the occurrence of graft nonunions, revision surgery, or glenoid component loosening when comparing type of graft or humeral component used. There was an association of revision surgery (P = .02) with ICBG and older age at the time of surgery (P = .02) and an association of transient neuroapraxia with onlay humeral components (P = .01) and workers' compensation cases (P = .04). CONCLUSIONS: There is a high union rate and low complication rate after bone grafting of the glenoid performed with RSA. Transient neuropraxias are the most frequent complication, but the majority resolve within the first postoperative year. These early findings can serve as the basis for future long-term, comprehensive analysis of complications and outcomes after bone grafting during RSA.

Capsular release following total shoulder arthroplasty: an analysis of early outcomes.

BACKGROUND: The purpose of this study is to analyze the outcomes of open and arthroscopic capsular release following total shoulder arthroplasty. METHODS: Over 15 years, 19 patients experienced persistent shoulder stiffness after anatomic total shoulder arthroplasty refractory to nonoperative treatment, requiring either open (n = 5) or arthroscopic (n = 14) capsular release. There were seven (39%) patients who had a prior diagnosis of stiffness before the primary arthroplasty. RESULTS: At a follow-up of 2.3 years (1-5.5), there were changes in range of motion, including forward flexion (77°-117°), abduction (49°-98°), external rotation (9°-19°), internal rotation at 0° (Sacrum to L1), and pain (4.1-2.3) scores (p < 0.01). There were seven (37%) patients that required a reoperation following the initial capsular release. The survival-free of reoperation at 2 and 5 years was 76% and 53%, respectively, while the survival-free of revision surgery at 2 and 5 years was 83%. Furthermore, three (16%) patients required a repeat capsular release. Overall, there were 11 (58%) complications, including stiffness (n = 9), infection (n = 1), subscapularis rupture (n = 2), glenoid loosening (n = 3), and pain with weakness requiring reoperation (n = 1). CONCLUSIONS: Shoulder stiffness after total shoulder arthroplasty is a very difficult pathology to treat, with high rates of complications and reoperations after capsular release. Overall, in patients that do not develop glenoid loosening, capsular release does improve the patient's pain and shoulder motion. Furthermore, when patients develop stiffness, it is critical to rule out other etiologies, such as glenoid loosening, prior to proceeding with capsular release. LEVEL OF EVIDENCE IV: Retrospective case series.

Surgical Treatment of Meniscal Extrusion: A Biomechanical Study on the Role of the Medial Meniscotibial Ligaments With Early Clinical Validation.

BACKGROUND: Meniscal extrusion refers to meniscal displacement out of the joint space and over the tibial margin, altering knee mechanics and increasing the risk of osteoarthritis. The meniscotibial ligaments have been shown to have an important role in meniscal stability. However, it remains unclear whether an isolated lesion of the medial meniscotibial ligaments will result in meniscal extrusion and whether repairing the detached ligament will reduce extrusion. HYPOTHESIS: A lesion of the medial meniscotibial ligament will result in meniscal extrusion, and repairing the joint capsule will eliminate the extrusion by returning the meniscus back to its original position. STUDY DESIGN: Controlled laboratory study. METHODS: Fresh-frozen human cadaveric knees (N = 6) were used for biomechanical testing. The test protocol involved 100 flexion-extension cycles. In full extension, meniscal extrusion was measured using ultrasound, in both an otherwise unloaded state and while subjected to a 10-N·m varus load. Each knee was tested in its native condition (baseline), after creating a detachment of the medial meniscotibial ligament, and finally with the joint capsule repaired using 3 knotless SutureTak anchors. We also performed a retrospective review of 15 patients who underwent meniscotibial ligament repair with a minimal follow-up of 5 weeks (mean, 14 weeks; range, 5-35 weeks). RESULTS: During biomechanical testing, the mean absolute meniscal extrusion at baseline was 1.5 ± 0.6 mm. After creation of the meniscotibial ligament lesion, the mean absolute meniscal extrusion was significantly increased (3.4 ± 0.7 mm) (P < .001). After repair, the extrusion was reduced to 2.1 ± 0.4 mm (P < .001). Clinically, a reduction in absolute meniscal extrusion of approximately 48% was reached (1.2 ± 0.6 vs 2.4 ± 0.5 mm preoperatively; P < .001). CONCLUSION: This study indicates that the medial meniscotibial ligaments contribute to meniscal stability as lesions cause the meniscus to extrude and that repair of those ligaments can significantly reduce extrusion. Early clinical results using this meniscotibial ligament repair technique support our biomechanical findings, as a significant reduction in meniscal extrusion was achieved. CLINICAL RELEVANCE: Our biomechanical findings suggest that repair of medial meniscotibial ligaments reduces meniscal extrusion and clinically may improve meniscal function, with the possible long-term benefit of reducing the risk for osteoarthritis.

Thrower's Exostosis of the Shoulder: A Systematic Review With a Novel Classification.

BACKGROUND: A variety of thrower's exostoses are grouped under the term Bennett lesion, which makes understanding diagnosis and treatment difficult. PURPOSE: To identify all types of reported thrower's and overhead athlete's exostoses and categorize them into a classification system to allow a morphology-based classification. STUDY DESIGN: Systematic review; Level of evidence, 4. METHODS: A systematic review of all articles pertaining to Bennett lesions and thrower's exostosis was performed. The classification and treatments were evaluated to describe the types, proposed causes, diagnosis, and treatment options. RESULTS: A total of 27 studies were included in the systematic review. The anatomic locations referenced in the study demonstrated posteroinferior, posterior, and posterosuperior glenoid lesions. Aggregate radiographic data demonstrated 158 of 306 patients (52%) with a thrower's exostosis of any type and location. Of these 158 patients with a radiographic lesion, 119 (75%) patients were symptomatic. The locations were posteroinferior in 110 patients (70%), directly posterior in 2 patients (1.3%), posterosuperior in 44 patients (28%), and unknown in 2 patients (1.3%). Avulsed lesions were present in 9 (5.7%) posteroinferior lesions, 0 direct posterior lesions, and 2 (1.3%) posterosuperior lesions. Treatment plans included both nonoperative and operative strategies, but operative intervention was more commonly reported for detached lesions. After operative intervention, only 61% of reported athletes returned to preinjury performance. CONCLUSION: Based on a comprehensive review of the literature, we identified several anatomic locations for a thrower's exostosis beyond the classic Bennett lesion. We categorized the reported exostoses into a new classification system for description of location and type (subperiosteal or free fragment) of the thrower's exostosis, which may be used to study future treatments. Current treatment strategies recommend that surgical treatment of thrower's exostosis is considered only after exhausting nonoperative management because reported return to sport is variable after surgery. The effectiveness of excision or repair for both subperiosteal and detached lesions has not been established.

Comparative Time to Improvement in Nonoperative and Operative Treatment of Rotator Cuff Tears.

BACKGROUND: Comparative time to recovery after operative and nonoperative treatment for rotator cuff tears is an important consideration for patients. Hence, we compared the time to achieve clinically meaningful reduction in shoulder pain and function after treatment. METHODS: From February 2011 to June 2015, a multicenter cohort of patients with rotator cuff tears undergoing operative or nonoperative treatment was recruited. After propensity score weighting, the Kaplan-Meier method was used to estimate the time to achieve a minimal clinically important difference (MCID), >30% reduction, and >50% reduction in the Shoulder Pain and Disability Index (SPADI) and the American Shoulder and Elbow Surgeons (ASES) scores. (In our analysis, both ASES and SPADI were coded such that a lower number corresponded to a better outcome; thus, the word "reduction" was used to indicate improvement in both ASES and SPADI scores.) A 2-stage test was conducted to detect a difference between the 2 groups. RESULTS: In this cohort, 96 patients underwent nonoperative treatment and 73 patients underwent a surgical procedure. The surgical treatment group and the nonoperative treatment group were significantly different with respect to SPADI and ASES scores (p < 0.05). The maximum difference between groups in achievement of the MCID for the SPADI scores was at 3.25 months, favoring the nonoperative treatment group. The probability to achieve the MCID was 0.06 (95% confidence interval [CI], 0.00 to 0.12) for the surgical treatment group compared with 0.40 (95% CI, 0.29 to 0.50) for the nonoperative treatment group. The surgical treatment group had a greater probability of achieving >50% reduction in SPADI scores at 15.49 months (0.20 [95% CI, 0.12 to 0.29] for the surgical treatment group compared with 0.04 [95% CI, 0.00 to 0.09] for the nonoperative treatment group). The surgical treatment group had a greater probability of achieving >50% reduction in ASES scores at 24.74 months (0.96 [95% CI, 0.84 to 0.99] for the surgical treatment group compared with 0.66 [95% CI, 0.53 to 0.75] for the nonoperative treatment group). The differences for >30% reduction in SPADI and ASES scores and the MCID for ASES scores were not significant. CONCLUSIONS: Patients undergoing nonoperative treatment had significantly better outcomes in the initial follow-up period compared with patients undergoing a surgical procedure, but this trend reversed in the longer term. These data can be used to inform expectations for nonoperative and operative treatments for rotator cuff tears. LEVEL OF EVIDENCE: Therapeutic Level II. See Instructions for Authors for a complete description of levels of evidence.